The invention relates to a device for generating a hollow plastic profile, in particular a plastic tube, with an extrusion die with a melt channel encompassing the extrusion axle, an extruder feeding the extrusion die with plastic melt and a suction device for the suctioning of air through the interior of the profile contrary to the direction of extrusion, and a corresponding method.
Air guidance systems for tube interior cooling are known from the prior art, for example DE 10 2008 047 207 A1 or DE 10 2008 047 211 A1. Here, air is sucked through the interior of the tube contrary to the direction of extrusion, in order to thus cool the tube. In known systems, the suction of air through the profile is arranged centrally in front of the extrusion die, for example a tube head, and the extrusion die itself has an aperture in order to be able to suck the air through up to the end of the extrusion line, so that the feeding of melt must take place laterally. On the one hand, this has disadvantages related to manufacture, because the extrusion die must be provided with a corresponding aperture and the necessary lateral supplying of the melt leads to a more complex die construction. On the other hand, this also entails disadvantages related to method, because owing to the lateral supplying of melt, for example the loss of pressure increases and flushing times, e.g. on colour change, become longer, but also the homogeneous melt distribution over periphery of the tube is made difficult, which can, in addition lead to losses of quality.